1. Field of the Invention
The present invention relates to a unit core of a motor and a method for manufacturing the same, and more particularly to a unit core in which a unit yoke has an elongated end extending from a central line connecting a center of a tooth to a center of a core formed by interconnecting a plurality of the unit cores, and a method for manufacturing the unit core.
2. Description of the Related Art
As shown in FIGS. 1 and 2, a core 10 of a conventional motor comprises a ring-shaped yoke 6T and a plurality of teeth 4 regularly spaced on the yoke 6T. The teeth 4 are formed on the yoke 6T along its circumference and spaced from each other by slots 2 formed therebetween. A coil (not shown) is wound on the teeth 2. Thus, when current flows in the coil, a rotating magnetic field is generated in the core 10, thereby causing the core 10 to be magnetized.
The core 10 of the motor is manufactured by forming a unit core assembly 30 by stacking a designated number of unit cores 20, the number obtained by dividing the ring-shaped core 10 into plural equal parts so that each part occupies an angle of 360°/the number of the slots 2, to a designated height (h), and interconnecting a plurality of the unit core assemblies 30 in a circumferential direction.
Herein, each of the unit cores 20 comprises a unit yoke 6 and a tooth 4 protruding from the unit yoke 6. The unit core 12 is symmetrical on a central line (L1) of connecting a center (C1) of the core 10 to a center (C2) of the tooth 4 of the unit core 20.
However, a plurality of the unit cores of the conventional motor are formed on an electric steel plate 25 so that one unit core 20 is opposite to a neighboring unit core 20a in orientation. Therefore, when the unit cores are made of the electric steel plate 25 by punching, a scrap 25a with a comparatively large size remains unused, thereby increasing the production cost.